Changes in the abundance and distribution of sav along Florida’s springs coast: a comparison based on aerial photography acquired in 1992 and 1999

Rapid, non-linear ecosystem alterations have been demonstrated in lakes, oceans, coral reefs, forests, and arid lands. These drastic changes in ecosystem state are often facilitated by loss of ecosystem resilience due to environmental degradation, and may be subsequently triggered by catastrophic perturbations. We present evidence for a dramatic ecosystem alteration in an estuarine system, as evidenced by population phase shifts of floral and faunal species in Chesapeake Bay due to a catastrophic disturbance, Hurricane Agnes, in 1972 subsequent to extensive environmental degradation and loss of resilience. A similar and long-lasting ecosystem alteration occurred in the seaside lagoons of Chesapeake Bay following a 1933 hurricane, the Storm King. These findings highlight the dynamic nature of estuarine ecosystems, whose community structure is governed jointly by chronic (e.g., overfishing, pollution) and acute (e.g., catastrophe) disturbances.

Chemical and molecular characterization of ontogenetic shifts in the chemical defense in Bugula neritina (Bryozoa)

Nicole Lopanik,¹* Niels Lindquist,² and Nancy Targett.^{1 1}University of Delaware College of Marine Studies, 700 Pilottown Rd, Lewes, DE 19958, USA; ²University of North Carolina Institute of Marine Sciences, 3431 Arendell St., Morehead City, NC 28557, USA.

Bugula neritina is a bryozoan found in temperate marine habitats throughout the world. Previous research has established that the physically vulnerable larvae of B. neritina are chemically distasteful to both vertebrate and invertebrate predators. Adults, however, do not possess this chemical defense. Bioassay-guided fractionation of larval extracts has resulted in the isolation of 3 active compounds. NMR and mass spectral data of the deterrent compounds, as well as other related but non-deterrent compounds indicate that they are bryostatins, which are polyketide macrolides. This is the first report of an ecological role for the bryostatins. Bryostatin levels fell sharply following larval metamorphoses so that 2-3 d old juveniles had undetectable levels of these compounds, coupled with a similar decline in deterrency. This precipitous decline in bryostatin levels following larval settlement and metamorphosis was not due to the increase in structural material per unit volume of juveniles or adults. It has been hypothesized that the bacterial symbiont, Canditatus Endobugula sertula, which resides in larval and adult tissue, produces the bryostatins. There are several possibilities to account for the ontogenetic changes in the concentrations of the unpalatable bryostatins. A molecular probe based on the ketosynthase module of the polyketide synthase was developed to determine when the gene is being expressed throughout the different stages. Two clone products were related to bacterial ketosynthases, and probes based on the sequences were made. One probe, when applied in RT-PCR shows expression in larval tissue. When applied using quantitative RNA techniques, this probe should allow us to distinguish how the differential production of these defensive compounds is regulated in B. neritina as it transitions through these vulnerable juvenile stages, and may lend insight into how E.sertula is involved in the biosynthesis of the bryostatins.


Mining biodiversity: molecular profiles of eubacterial associates of Caribbean marine sponges

Jose V. Lopez,* Cheryl L. Peterson, P. J. McCarthy, Holly Page, T. Pitts, and Shirley A. Pomponi. Division of Biomedical Marine Research, Harbor Branch Oceanographic

Institution, 5600 US Hwy 1, Ft. Pierce, FL 34946, USA.

Our laboratory has been characterizing the microbial consortia of several different Caribbean marine demosponge species using molecular genetics techniques as part of a survey of cryptic biological diversity in the sea. Our primary interests have been to determine the extent of specific microorganismal associations (or "symbioses") with sponges and consequently any metabolic mutualisms and exchanges that may stem from these associations, especially in the context of secondary metabolite biosynthesis. The primary methods used for the identification of eubacterial isolates was amplification of 16S-like rRNA and polyketide synthase (PKS) gene fragments using the Polymerase Chain Reaction (PCR), DNA sequencing, REP-PCR fingerprinting and molecular phylogenetics analyses. Congruence between the disparate gene and template datasets is explored for molecular evolutionary implications, such as the potential of horizontal gene transfer or molecular adaptations (positive selection). 16S rRNA profiles were also

compared between cultured isolates and uncultured environmental clones. Results to date confirm a wide phylogenetic diversity of microbes that are positive for polyketide biosynthetic gene sequences within the sponge hosts sampled. Most 16S rRNA gene sequences from uncultured DNA samples clustered separately from isolates. Cultured alpha proteobacteria appeared ubiquitous among all hosts and closely related by their 16S rRNA genes. In contrast, Gram+, gamma, beta and cytophaga eubacterial clades exhibited deep roots and long branch lengths, suggesting novel isolates and/or clones, or perhaps relative genetic isolation stemming from specific symbioses or co-evolution.

Assessing the roles of habitat complexity and scale in oyster reef restoration

Mark Luckenbach,* P. G. Ross, Alan Birch, Stephanie Bonniwell, and Susan Spears. Virginia Institute of Marine Science, Eastern Shore Laboratory, College of William and Mary, Wachapreague, VA 23480, USA.

Current attempts to restore biogenic oyster reefs along the US Atlantic coast rely on the placement of material (shell, limestone marl, concrete and other substrate) on the seabed to provide foundations for reef development. Unfortunately, substrate is costly, oyster recruitment rates are reduced over historical levels and oyster mortalities are often high. Thus, there is a premium on optimizing the habitat design to maximize the recruitment and survival of oysters. We have conducted manipulative experiments over varying scales to test the effects of position in the estuary (1 – 10 km), reef size (100’s of m), position on the reef (10’s of m), interstitial space (cm’s) and surface rugosity (mm’s) on the settlement and early post-settlement survival of oysters. Reef foundations of varying sizes were established in a large-scale, replicated block design in a tributary of the lower Chesapeake Bay and oyster recruitment and early post-settlement survival patterns determined. In another experiment we manipulated substrate particle size (and thus interstitial space) and particle surface complexity (rugosity) to elucidate the effects of habitat complexity on the scale of individual oysters. Our results reveal significant variation in recruitment and early post-settlement survival from the largest basin-wide scale to small-scale effects of interstitial space and surface rugosity. These findings provide insights into how habitat complexity can be manipulated to enhance restoration efforts.

The role of post-settlement mortality in recruitment of encrusting organisms associated with intertidal and subtidal sabellariid reefs in Boynton Beach, Florida

Daniel A. McCarthy.* Smithsonian Marine Station at Fort Pierce, 701 Seaway Drive, Fort Pierce, FL 34949, USA.

Seasonal recruitment patterns of encrusting organisms into intertidal and subtidal sabellariid worm reef habitats off Boynton Beach, Florida were followed from June 1997 to January 2000. Caged and uncaged settlement plates were exchanged every month to determine the effects of predation on the number of species, and on the abundance of several solitary species. During this study, twenty-three species of encrusting organisms were observed to recruit on settlement plates. The sabellariid Phragmatopoma l. lapidosa was the encrusting species most commonly observed settling during the study. The number of species recruiting was usually higher in subtidal than intertidal habitats. Many of the encrusting species recruited to both habitats, although they generally were found at greater abundance in one habitat. Recruitment occurred on all plate types, but was usually higher on the control and enclosed plates than on the exposed plates. For most species differences in recruitment patterns between intertidal and subtidal habitats could not be explained by predation on recruits. During peak recruitment, P. l. lapidosa may limit recruitment of other encrusting species by covering over them. Additionally, high juvenile mortality in these other species is caused by frequent sand scouring or burial.


The Keys Marine Laboratory: a research and education facility in the Florida Keys

Kevin McCarthy.* Florida Institute of Oceanography, Keys Marine Laboratory PO Box 968, Long Key FL 33001, USA; e-mail [e-mail].

The Keys Marine Laboratory is a state supported, university affiliated research and education facility. The lab is located in the Florida Keys adjacent to the extensive seagrass and mangrove systems of Florida Bay and is near the Florida reef tract. Researchers have used the KML in a variety of ways ranging from a base for sample collection to a site for extensive mesocosm based manipulative experiments. During the five-year period, 1996-2000, there were 167 research projects conducted through KML and 33 additional projects for which more than 10,000 specimens were collected by laboratory staff. Those projects have resulted in over 300 publications, abstracts, and reports. The KML has also served as the location for valuable contributions to the education and training of undergraduate and graduate students. In the past five years 101 separate educational institutions have utilized the KML totaling 225 student groups and more than 15,000 student days at the facility. The lab includes nine buildings on eight acres situated between US Highway 1 and Florida Bay and is a two-hour drive from Miami. Approximately 25% of the property consists of salt water holding facilities, a 2,082,400 liter series of five connected flow-through shallow ponds and a variety of tanks ranging in size from 61 to 3,800 liters. The buildings include two dormitory units with cooking facilities, accommodating up to 24 residents. Also on site are administrative offices, a small conference room, a chemistry laboratory, a diving locker with compressor, laundry facilities, a small machine shop, a classroom/conference room, computer laboratory, wet laboratories and dry laboratories. Two additional buildings are used to house groups of from one to six visiting scientists requiring long-term accommodations. Other resources of this full service marine laboratory include marina facilities and a fleet of eight vessels from 10 to 26 feet in length.